Open Blender GUI from .py script
Blender built as a python module does not support a gui interface, it's runs as if blender was started in background mode. You can verify this by checking the background value

&gt;&gt;&gt; import bpy
&gt;&gt;&gt; bpy.app.background
True


If you are working on an addon, you can edit the scripts and then  disable/enable the addon to re-load the changes in blender. You may also want to look at the notes on remote debugging using eclipse.

You can open a text file in blender and run it as a script, you can reload the file after changes and then run it again. You may find the addon I link to in this answer helpful, the other answer there shows how to run a script straight from the file in blenders python console.